Unless you move close to the screen you can't see the pixels so upscaling even with the simple upscale of same 4 dots for 1 dot works.
It's the color that seems to matter here as you read articles like https://www.cnet.com/news/budget-tv-resolution-rumble-720p-plasma-vs-4k-led-lcd/
We also have the https://carltonbale.com/does-4k-resolution-matter/ charts. So if you sit a normal distance back the average human can't see the pixels.
This is why when selling 4K UHD you take the buyer up close to the screen.
Both Sony and LG seem to have the best OLED picture. Which brand does a better job with 4K upscaling? The Sony website advertises its computer abilities to do this, whereas there's no obvious discussion of this feature at LG. With most content still at 1080, I would think this to be an important feature.

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